Support ‘apt-get changelog’

[andersk]

Natty and wheezy support apt-get changelog ( DebianBug:526990). Presumably we can make this work for Debathena packages by adding changelogs to our pool directories.

$ apt-get changelog debathena-dent
Err Changelog for debathena-dent (http://changelogs.ubuntu.com/changelogs/pool/debathena/d/debathena-dent/debathena-dent_10.0.1~ubuntu11.04~0.1/changelog)
  404  Not Found
Err Changelog for debathena-dent (http://debathena.mit.edu/apt/pool/debathena/d/debathena-dent/debathena-dent_10.0.1~ubuntu11.04~0.1.changelog)
  404  Not Found
E: changelog for this version is not (yet) available; try https://launchpad.net/ubuntu/+source/debathena-dent/+changelog

[andersk]

geofft points out that reprepro ≥ 4.10.0 (quantal+) comes with a  /usr/share/doc/reprepro/examples/changelogs.example.gz that looks like it does what we want.